The invention is directed to spandex. More particularly, the invention provides spandex that is made from one or more polyols that have an aromatic functionality. The spandex of the invention has improved resistance when exposed to high temperature, including high temperature dyeing, with minimal loss of desirable physical properties, such as elastic recovery.
Spandex is a long-chain synthetic polymer fiber comprising at least 85% by weight of a segmented polyurethane. As shown in FIG. 1, spandex has two segments: a soft, rubbery segment A and a hard segment B. The soft segment A is generally made of a polymeric glycol which allows the fiber to stretch and to recover its original shape. The hard segment B is generally made of a polyurethane which provides the fiber with rigidity and tensile strength. The polyurethane can be a polyurethaneurea, which is a sub-class of polyurethane.
The polyurethane is generally made by reacting a polymeric glycol with a diisocyanate to form a capped polymeric glycol. If a polyurethane without urea is desired, the capped polymeric glycol can be reacted with a diol chain extender and, optionally, a monofunctional chain terminator either in the melt or after being dissolved in a solvent. If a polyurethaneurea is desired, the capped polymeric glycol can be dissolved in a solvent before being reacted with a diamine chain extender and, optionally, a monofunctional chain terminator.
Spandex is typically prepared by reaction spinning, melt-spinning, dry-spinning, or wet-spinning a polyurethane solution either into a column filled with a hot inert gas such as air, nitrogen or steam or into an aqueous bath to remove the solvent followed by winding up the fiber. Methods for reaction spinning, melt spinning, dry spinning and wet spinning are known in the art.
Dry-spinning is the process of forcing a polymer solution through spinneret orifices into a shaft to form a filament. Heated inert gas is passed through the chamber, evaporating the solvent from the filament as the filament passes through the shaft. The resulting spandex can then be wound on a cylindrical core to form a spandex supply package.
Because of its good elasticity and tensile strength, spandex has been used to make articles of clothing, such as intimate apparel, swimwear, sportswear, sheer hosiery, socks, dresses, suits, outerwear, and the like. Spandex has also been used in disposable personal care products, such as baby diapers, feminine care products, adult incontinence garments, protective masks, medical garments, industrial garments and the like. Spandex can also be used in upholstery and in other commercial and industrial applications. Spandex is generally blended with other natural or man-made fibers, such as nylon, polyester, cotton, wool, silk and linen.
Spandex tends to lose elasticity when subjected to high temperatures during the dyeing process. In view thereof, there is a need in the art to produce spandex that has excellent elasticity after being subjected to the high temperatures associated with the dyeing processes. The invention is directed to this, as well as other, important ends.
In one embodiment, the invention provides a spandex comprising a polyol having at least one aromatic functionality, such as a phenol.
In another embodiment, the invention provides a spandex that is the reaction product of a polymeric glycol, a polyol having at least one aromatic functionality, an organic diisocyanate, and at least one chain extender.
In another embodiment, the invention provides a method for making spandex by mixing a polymeric glycol and a polyol having an aromatic functionality to form a resin mixture; mixing the resin mixture with an organic diisocyanate to form a capped-glycol, polymerizing the capped-glycol to form a polyurethane, and then forming the spandex from the polyurethane.
These and other aspects of the invention are described in more detail herein.